The proposal, supported by the gun-rights groups and opposed by Minnesota's law-enforcement organizations, would have expanded the legal justification for citizens who use deadly force in threatening situations.

The bill, sponsored by Rep. Tony Cornish, R-Good Thunder, and Sen. Gretchen Hoffman, R-Vergas, was the top priority of the National Rifle Association and drew some DFL votes in addition to near-unanimous Republican support. The measure passed by votes of 40-23 in the Senate and 85-47 in the House.

It would have changed the legal definitions of self-defense for someone facing a serious threat in their homes, and would have expanded this "castle doctrine" to cars, motor homes, boats and even tents.

It would have done away with a person's duty to retreat when facing a threat in public places, which supporters called the "stand your ground" concept. It would also have legalized concealed-weapons permits issued by all states, regardless of their standards in granting permits, and limited the situations in which police can temporarily remove weapons from homes in volatile situations.

Law enforcement organizations strongly condemned the proposal, saying it could risk officers' lives.

Dayton made his veto by letter without commenting publicly.

In his veto letter, Dayton said, he had to honor the opposition of law enforcement.

"The MN Police and Peace Officers Association, the MN Chiefs of Police and the MN Sheriffs Association represent the men and woman who risk their lives every day and night to protect the rest of us. When they strongly oppose a measure, because they believe it will increase the dangers to them in the performance of their duties, I cannot support it," Dayton wrote.

Rep. Tony Cornish, a Republican from Good Thunder, said the opposition stemmed from the executives of law enforcement organizations "not the rank and file." He said that the measure may take some time to become law but it will be back.